Actually the main problem with my terrain was that I got a bit too creative and added a load of towns I built from the tiles that make up the strat cities. Many of these were placed between spawns and fields to give GVs some different terrain to fight through, some had rivers with bridges to cross too. I figured that as these city tiles were in MA terrains anyway, it would be OK to use them this way. Unfortunately it wasn't OK as all the city pieces have hidden links to the strat system. HT suggested a way I might get round this and I've been reworking the terrain in between skinning jobs.
Otherwise I've had to alter the texturing on the terrain to blend in with the new fields, town and port, as well as altering the coastlines slightly to match the latter. There were also some mistakes I'd made in object settings that I've had to fix. It is mostly done now, I'm currently bug testing prior to resubmitting.
Building an MA terrain is a frequently frustrating experience as the editors are quirky, buggy and poorly documented. There tends to be a lot of boring repetitive stuff to do that could be better automated in software. The interesting "art" part of building the terrain for me is working out the field layout, as well as contouring and texturing the terrain. However this tends to be only a small percentage of the number of hours involved, the rest is the boring repetitive stuff. I've been working on this terrain on and off for over three years now. Some of that time involved several rebuilds when HTC altered the way the terrain was handled, but mostly its just lack of time. After a while it gets to the point where you carry on just to avoid having lost all the work you've done.